Precision cosmology

The good agreement between large-scale observations and the predictions of the now-standard ΛCDM theory gives us hope that this will become a lasting foundation for cosmology. After briefly reviewing the current status of the key cosmological parameters, I summarize several of the main areas of possible disagreement between theory and observation: big bang nucleosynthesis, galaxy centers, dark matter substructure, and angular momentum, updating my earlier reviews [Primack, J.R., 2004. In: Ryder et al., S.D. (Eds.), IAU Symposium 220 Dark Matter in Galaxies (Astron. Soc. Pacific), p. 53 and p. 467, and other articles in that volume. Primack, J.R., 2003. Status of Cold Dark Matter Cosmology. In: Cline, D. (Ed.), Proceedings of 5th International UCLA Symposium on Sources and Detection of Dark Matter, February 2002. Nucl. Phys. B, Proc. Suppl., 124, 3 (astro-ph/0205391)]. The issues in all of these are sufficiently complicated that it is not yet clear how serious they are, but there is at least some reason to think that the problems will be resolved through a deeper understanding of the complicated astrophysics involved in such processes as gas cooling, star formation, and feedback from supernovae and AGN. Meanwhile, searches for dark matter are dramatically improving in sensitivity, and gamma rays from dark matter annihilation at the galactic center may have been detected by H.E.S.S.